Available as an assembled Module and as a DIY project.
This Module is currently available.
Expander for ST Modular Karl Stereo Filter
The "Karl Mode Selector" gives you front panel control over the modes and alternative audio input for the right chanel that can be activated via switch. Modes: Low Pass, High Pass, Phaser Mode, Overdrive Mode
This Module is not sold seperatly, it´s component of the DIY Kit.
ST Modular Karl Mode Selector Expander